Vision-based mechanisms of time perception

Abstract

Perceived duration of brief intervals can be altered in a specific spatial location in the
visual field by adaptation to oscillatory motion or flicker (Johnston et al, 2006, 2008). In
the first experiment here, the spatial tuning of adaptation-based temporal distortions was
investigated by varying the spatial separation of adaptor and test. It was found that
adaptation-based apparent duration compression is tightly tuned to the location of the
adaptor and that the effects of adaptation on perceived duration are dissociable from those
on temporal frequency although the spatial tuning of these effects was similar. In a second
experiment, the frame of reference (retinotopic versus spatiotopic) of adaptation effects
was investigated using pursuit and saccadic paradigms. It was observed a robust time
compression following a purely retinotopic adaptation. In two different saccadic
paradigms, no significant effect was observed after spatiotopic adaptation. No interocular
transfer was found. In a third experiment, the effect of the luminance signal on adaptationbased
duration compression was investigated using luminance-modulated and isoluminant
stimuli. It was shown that the apparent duration compression following temporal frequency
adaptation is specific to luminance-modulated stimuli and that the effect disappears at
isoluminance. The differences in visibility between luminance-modulated and isoluminant
stimuli could not explain the discrepancy. At isoluminance, duration compression was
recovered for chromatic backgrounds. The final experiments investigated the effect of
simultaneous surrounds on the perceived duration of inner patches. It was found that
perceived duration of a mid-temporal frequency counterphase modulated flicker is almost
significantly expanded if embedded within a high temporal frequency context; whereas a
low temporal frequency context can only induce a mild expansion. In an adaptation
paradigm, counterphase modulated flicker was found to induce smaller duration
compression compared to drifting stimuli. These results provide further evidence for a
difference between mechanisms modulating duration and temporal frequency.